Texas Instruments LM3411M5X-5.0/NOPB

Overview

LM3411M5X-5.0/NOPB from Texas Instruments is a precision 5-V fixed-output shunt regulator with ±0.5% initial tolerance (A-grade), designed specifically to drive optocouplers in isolated DC-DC feedback loops. It features an open-emitter NPN output capable of 15 mA sink current, internal bandgap reference with curvature correction, and externally accessible compensation pin for loop stability tuning - used in flyback converters delivering 5 V at 250 mA or 1.5 A.

For engineers reviewing the LM3411M5X-5.0/NOPB datasheet, LM3411M5X-5.0/NOPB pinout, LM3411M5X-5.0/NOPB application, or LM3411M5X-5.0/NOPB equivalent, key selection criteria include regulation accuracy over –40°C to +125°C, COMP pin accessibility for closed-loop compensation, SOT-23 package thermal performance (R_θJA = 178.6°C/W), and compatibility with TI's SIMPLE SWITCHER® regulators in precision buck/flyback topologies.

Technical Context

The LM3411M5X-5.0/NOPB implements a precision shunt regulation architecture centered on an internally compensated op-amp and trimmed bandgap reference. Its +IN pin senses regulated voltage directly, while the COMP pin provides direct access to the op-amp's inverting input for external RC compensation networks - enabling stable control loop design in isolated flyback systems.

It operates as a two-terminal shunt device with three functional nodes: +IN (voltage sense), GND (reference return), and OUT (NPN emitter output). The internal 94 kΩ feedback resistor sets the 5-V regulation point, and its temperature coefficient is characterized to ensure <±1% total error across –40°C to +125°C operating range without external trimming.

Key Specifications

Pinout & Package

LM3411M5X-5.0/NOPB is housed in a 5-pin SOT-23 (DBV) package measuring 2.90 mm × 1.60 mm, optimized for space-constrained isolated power designs. Pin 3 is NC but must be soldered to PCB for thermal conduction.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar shunt regulator applications.

Compared with TL431ACDBVR and LM4040C50IDBZR, LM3411M5X-5.0/NOPB uniquely combines factory-trimmed 5-V regulation, integrated NPN output, and accessible COMP pin - reducing component count, improving loop stability, and eliminating external trimming in isolated DC-DC feedback paths.

Availability

LM3411M5X-5.0/NOPB is available at Aetrix Electronics and suitable for isolated flyback converters, precision buck regulators, LDO reference enhancement, and negative-voltage flyback systems requiring stable component supply and long-term production continuity.

Supply support for LM3411M5X-5.0/NOPB includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor company specializing in analog, embedded processing, and power management technologies, with over 90 years of innovation in precision analog ICs.

The LM3411 product line delivers precision shunt regulation for isolated power supply feedback, targeting high-accuracy, low-component-count solutions in space-constrained industrial and telecom power systems.

FAQ

What is the function of the COMP pin on the LM3411M5X-5.0/NOPB?

The COMP pin on the LM3411M5X-5.0/NOPB is the inverting input of the internal error amplifier, exposed for external loop compensation. Connecting an RC network (e.g., 10 nF capacitor) between COMP and OUT sets dominant pole frequency and phase margin - critical for stable regulation in 80 kHz–500 kHz flyback converters. This feature is absent in standard shunt references like TL431 or LM4040.

Can the LM3411M5X-5.0/NOPB drive an optocoupler directly?

Yes, the LM3411M5X-5.0/NOPB can drive common optocouplers such as PC817 or TLP521 directly. Its open-emitter NPN output sinks up to 15 mA with 1.2 V saturation voltage at full load, providing sufficient current and headroom for typical optocoupler LEDs. No external transistor buffer is required, simplifying isolated feedback design.

What is the maximum input voltage rating for the LM3411M5X-5.0/NOPB?

The absolute maximum input voltage (applied to the +IN pin) for the LM3411M5X-5.0/NOPB is 20 V. Exceeding this may cause permanent damage. In normal operation, +IN is held at 5 V by regulation; transient overvoltage events (e.g., during startup or fault conditions) must be clamped or limited externally to stay within this 20-V limit.

How does the LM3411M5X-5.0/NOPB achieve ±0.5% regulation accuracy?

The LM3411M5X-5.0/NOPB achieves ±0.5% regulation accuracy via a factory-trimmed, curvature-corrected bandgap reference and matched internal feedback resistors (94 kΩ nominal for 5-V version). This trimming occurs at wafer test and is guaranteed over temperature (–40°C to +125°C) using statistical correlation - eliminating need for external precision resistors or post-assembly calibration.

Is the LM3411M5X-5.0/NOPB compatible with TI's SIMPLE SWITCHER® regulators?

Yes, the LM3411M5X-5.0/NOPB is explicitly designed for interoperability with TI's SIMPLE SWITCHER® family, including LM2574, LM2575, LM2576, and LM2577. It replaces their internal reference and error amplifier, enabling tighter output regulation (±0.5%) and remote sensing - as demonstrated in TI's Application Report SNVS113F with schematics for 5-V/1-A buck and 5-V/1.5-A flyback designs.